Biochemical Composition of Prostate Core-Needle Biopsies Before and After a Single Fraction of 13.5 Gy: A Raman Spectroscopy-Based Study

Abstract

High dose rate brachytherapy (HDR-BT) is an attractive option for patients with favourable-risk intermediate-grade prostate cancer. However the relationship between radiation dose and the biochemical response of tumours remains poorly understood. The aim of this study was to investigate the tissue composition of prostate core-needle biopsies, before and after a single dose (13.5 Gy) of HDR-BT using Raman Spectroscopy (RS) and Group and Basis Restricted Non-Negative Matrix Factorisation (GBR-NMF) modelling. RS was used to measure the spectral profiles of benign and malignant regions of prostate tissue. GBR-NMF was employed to derive biochemical profiles from Raman spectra of core-needle biopsies, encompassing both benign and malignant areas, from patients with intermediate risk prostate cancer (PCa). Thirty-four biochemicals were included in the RS evaluation of 40 biopsy samples from 20 patients. Eight biochemicals were significantly differentially expressed between pre-and post-HDR-BT benign tissue (13.5 Gy single fraction) : citric acid, collagen, cysteine, DNA, glycerol, palmitic acid, tryptophan, and lycopene (by Mann-Whitney U Test). The model identified phenylalanine, stearic acid and retinol to be differentially expressed in malignant tissue after a single dose of 13.5 Gy high dose rate brachytherapy. β -Carotene was found to differ in expression between benign and malignant prostate tissue, irrespective of radiation exposure. Carotenoids and phospholipids may influence the tumour microenvironment (TME) through several mechanisms that affect cancer progression and response to treatments like radiation therapy. These biochemical changes could identify potential therapeutic targets for a personalised radiation treatment approach.